1. Field of the Invention
This invention relates to electric motors and, more particularly, to an electric motor having an adjustment member situated on an armature shaft and cooperating with another member to reduce or eliminate armature axial end play, thereby reducing noise, heat and undesired vibration.
2. Description of Related Art
A conventional motor shaft is fastened to a driven member, such as a window lift linkage or assembly, a drive gear or the like, a blower wheel or fan or the like, so that rotational motion can be transferred from the shaft to the driven member.
Due to various factors, such as tolerances in the length of the lamina stack, bearings, motor end caps, end laminas, motor frame, commutator axial position, and the like, a gap, or often called end play, can result between the bearing axial thrust surface(s) and the axial thrust surface(s) on the armature. End play that is excessive in nature can cause the armature assembly to travel axially between the bearings which support the armature shaft, potentially causing undesirable noise and/or vibration. Too little end play, or sometimes called negative end play, can cause undesired noise, heat, and premature failure.
Automotive manufacturers and motor manufacturers have undertaken efforts to minimize this end play distance. One conventional approach incorporates either hard or resilient washers that are positioned between the armature and bearing thrust surface(s) to resist movement of the armature relative to the frame. Other noise suppression approaches include the use of noise absorption materials and barriers within the motors. Still another approach is to assemble a retainer to the external portion of the armature shaft, in close proximity to the external face of one of the bearings. Armature axial travel is limited in one direction by the retainer on the outside of the motor and in the other direction by the internal thrust surface on the armature.
There is a need to provide a further solution for effective suppression of vibration and noise in a new approach to reducing or eliminating end play in an electric motor.